1. Field of the Invention
This invention pertains generally to quantization within multimedia bit-streams, and more particularly to a method of performing quantization without utilizing division instructions.
2. Description of the Background Art
Quantization is performed within multimedia bit-streams, such as MPEG-2, and protocols having a similar architecture, to convert a block of discrete transform (DCT) coefficients into integers by dividing quantizer step sizes. Applications for quantization include an assortment of video post-processing equipment for the display of digital video signals. The quantizer step sizes in the block are specified by two elements: (1) a weighting matrix that is utilized to modify the step sizes within a block, and (2) a scale factor that is utilized to modify the step sizes at the cost of only a few bits, which is in contrast to the encoding of an entirely new matrix. Corresponding to the two elements specified by the quantizer step size, two separate steps are contained in the implementation of the MPEG-2 quantizer, and both steps involve an integer division which is the toward-zero integer truncation of the corresponding floating-point division. It will be appreciated that in terms of processor bandwidth, integer divisions are expensive operations in relation to other instructions, such as shift, multiply, and so forth. Furthermore, it is difficult to implement quantizers for MPEG-2, and similar protocols, which take full advantage of available SIMD instructions while providing accurate results.
Therefore, a need exists for a quantization method that efficiently executes on processors having SIMD, or similar, architectures without sacrificing the precision of the result. The present invention satisfies those needs, as well as others, and overcomes the deficiencies of previously developed solutions.